Drawing for Improvements in Telegraphy
After years of experiments, Alexander Graham Bell devised the first apparatus to transmit human speech via machine. Bell patented his “Improvements in Telegraphy" (aka the telephone) on March 7, 1876, making it “…possible to connect every man’s house, office or factory with a central station, so as to give him direct communication with his neighbors.” His work culminated in one of the most profitable and contested of all 19th-century patents.
From the series: Patent Case Files, compiled 1836 - 1993. Records of the Patent and Trademark Office, 1836 - 1978.